Hi,
I have a question about the below circuit of LT3080, what is the purpose of D1?
Is that for discharge C2 when the Vin disappeared?
Because D1 will affect the accuracy of Vout, I do not want to add D1。
Best Regards,
Leo
Thanks for the post. Yes, the diode D1 you show will affect accuracy. I show how much a silicon diode can leak in the image below. As far as I know, the purpose of D1 is to prevent SET from being held…
This post discusses the need to clamp OUT to SET - usually when a voltage is applied to SET - but your situation may apply as well. The post is titled "LT3083 output not zero when set pin grounded".…
Thanks for the post. Yes, the diode D1 you show will affect accuracy. I show how much a silicon diode can leak in the image below. As far as I know, the purpose of D1 is to prevent SET from being held up if IN=VCONTROL is forced low. Actually, if IN=VCONTROL is forced low, OUT will also be forced low because there is a parasitic diode from OUT to IN on the LT3080, similar to the parasitic diode I discuss in this post titled "Disable LT3083".
Very thank you for your reply.
ABS.max of SET pin voltage is just ±0.3V relative to OUT.
it seems that If I use a little big C2 for soft-start, that means it is a must to use D1 to protect SET pin when IN=VCONTROL is forced low. this will be a weak point.
Best regards,
Hi Arad,
Please let me ask one more question.
Because ABS.max of SET pin voltage is just ±0.3V relative to OUT, is it necessary to place a diode between SET pin and OUT pin?
Thanks,
This post discusses the need to clamp OUT to SET - usually when a voltage is applied to SET - but your situation may apply as well. The post is titled "LT3083 output not zero when set pin grounded".
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